Arrangements of this type, which may also be referred to as marking sleeves, have long been used for marking in particular electric wires and cables, but are also used for marking pneumatic and hydraulic pipes.
By virtue of the inner yoke-shaped part, the web portion of which forms a support for a wire which is guided through the marking sleeve, a number of bellows-like folds are formed, which afford an expansion possibility for the sleeve. One and the same marking sleeve can then be used for wires of diameters which vary within a given range. It is therefore possible to cover a diameter range from roughly 1 mm to roughly 16 mm by using marking sleeves of four standard sizes.
The marking sleeves can either be made in the form of relatively small rings, each intended to bear a marking symbol, a number of rings then being positioned next to one another on a wire so as to bring about a sequence of a number of marking symbols, or alternatively the marking sleeve can be made of greater length, in which case one and the same sleeve can bear a sequence of marking symbols.
The marking symbols can either be printed directly onto the upper part of the sleeve, which part connects the upper edges of the outer legs of the sleeve, or alternatively be printed on separate labels which are inserted into an upper, longitudinal pocket of the sleeve. The sleeves are suitably manufactured by extrusion of a relatively soft plastic material.
Marking sleeves of the type indicated above, which are each to be capable of being used on wires of different diameters, should have two characteristics, which can be difficult to combine. The first characteristic is that the sleeves, after they have been threaded onto a wire from one of its ends, are to be secured in the desired position without risk that they will rotate on the wire or be displaced along it, which requires good friction. The second characteristic, which is difficult to combine with the first, is that the sleeves are to be easy to thread onto a wire, that is to say the friction between the sleeve and the wire is to be as low as possible during threading-on. This applies particularly in the case of longer sleeves.